hubsand
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 p.2 #22 · Where does the 3D look come from? | |
There seem to be two unrelated discussions going on here: there's no mystery about contriving a scene in which one element 'pops out of the foreground': it's purely a function of DOF and contrast. Large format images simply have less DOF, hence the mojo.
The deeper and more interesting question addresses what's going on when two lenses shoot an identical scene with the same lighting at the same focal length and aperture, yet one more vividly depicts a plausible sense of 3D space, or plasticity. As has been suggested, this appears to be something of a black art identifiable by German (especially Zeiss) glass.
To me the quality is akin to what audiophiles, in similar pursuit of fidelity to reality, call 'presence' – valve amps and high sensitivity speakers do the trick. Whatever the knack is, it seems easier to achieve with longer than shorter lenses. At 28mm there are many fine lenses but the Canon, Nikon and Olympus models give results that look like photographs shot with fine lenses; with Zeiss and Leica it's like being there.
However, the phenomenon is visible in the digital realm, so we might begin by following Adobe's original Photoshop maxim about edges and transitions. If you look at these 600% crops taken from a lens that has the mojo (Zeiss 28mm, right) and one that doesn't (Canon 17-40, left) you'll notice that the Zeiss describes transitions between strongly contrasting colours in fewer pixels, and that every one of those pixels is more strongly defined: the mid-tones particularly are spread apart, polarised more strongly towards lights and darks, and have greater luminosity.
The 'hi-fi' analogy is apt here, because the 'effect' seems to be to do with how closely the lens and camera matching your brain's impression of the scene via the eyes. Most glass delivers a tell-tale flattening of these differences that immediately signals 'artifice' to the viewer. But when the lens is well enough designed to transmit that colour and accutance untainted, the brain responds differently to it, and has a harder job recognising it isn't 'real'. This is evidently very difficult/expensive to do: eyes, like ears, take some fooling.
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